Corbel and Henry Parasites & Vectors 2011, 4:37
http://www.parasitesandvectors.com/content/4/1/37
MEETING REPORT
Open Access
Prevention and control of malaria and sleeping
sickness in Africa: Where are we and where are
we going?
Vincent Corbel1,2*, Marie-Claire Henry1,3
Abstract
The International Symposium on Malaria and Human African Trypanosomiasis: New Strategies for their Prevention &
Control was held 7-8 October, 2010 in Cotonou, Benin with about 250 participants from 20 countries. This scientific
event aimed at identifying the gaps and research priorities in the prevention and control of malaria and sleeping
sickness in Africa and to promote exchange between North and South in the fields of medical entomology,
epidemiology, immunology and parasitology. A broad range of influential partners from academia (scientists),
stakeholders, public health workers and industry attempted the meeting and about 40 oral communications and
20 posters were presented by phD students and internationally-recognized scientists from the North and the
South. Finally, a special award ceremony was held to recognize efforts in pioneer work conducted by staff involved
in the diagnostic of the Sleeping illness in West Africa with partnership and assistance from WHO and SanofiAventis group.
Background
For about ten years now the United Nations Millennium
Declaration defined the Millennium Development Goals
of which some are to promote the fight against poverty,
gender equality, accessibility to education and improvement in health. For health, particularly in infectious diseases, one of the clearly enunciated goals is to halt and
begin to reverse the incidence of malaria by 2015, and
bring hitherto neglected tropical diseases under control
in the same time-frame [1]. However, just four years
before the deadline, both malaria and human African
trypanosomiasis (HAT) are still overwhelming developing countries. The spread of resistance–both to drugs by
the parasites and to insecticides by the vectors–is a
major concern which constantly raises questions about
the effectiveness of “current” control strategies.
In this context, it is the right time to assess the limitations and gaps in knowledge of the prevention and control of these diseases particularly in Africa. For example,
what are the main causes of emergence and/or spread?
Do we have effective screening methods/strategies for
* Correspondence: [email protected]
1
Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604,
Cotonou, Bénin
Full list of author information is available at the end of the article
detection of parasites, especially for HAT? Do we have
significant progress in malaria vaccination, notably in
vaccines targeting the most vulnerable groups? Do we
have new/alternative prophylactic drugs for pregnant
women to counteract the growing resistance of malaria
parasites to sulfadoxine-pyrimethamine (SP)? Are there
any new ‘weapons’ to ensure effective control of malaria
transmission and to manage the development of pyrethroid-resistance in malaria vectors? These issues are
particularly relevant to address considering the mobilization of funds by international organisations such as the
Bill & Melinda Gates Foundation and World Health
Organization (WHO) that are planning ambitious programmes of elimination and even eradication for malaria
and sleeping sickness.
Report
The International Symposium on Malaria and Human
African Trypanosomiasis: New Strategies for their Prevention & Control that was held in Cotonou, Benin on
the 7th and 8th of October 2010 http://www.symposiumpalutha.org aimed at identifying the gaps and research
priorities in the prevention and control of malaria and
sleeping sickness in Africa and to promote exchange
between North and South in the fields of entomology,
© 2011 Corbel and Henry; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Corbel and Henry Parasites & Vectors 2011, 4:37
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epidemiology, immunology and parasitology (see additional files 1 &2).
The discussion in the first session of the symposium
showed that significant advances in the prevention and
control of sleeping sickness, made in West Africa, are
opening the way to the possibility of eradication in the
medium term [2,3]. Measures were proposed to help
realize this ambition. It has been proposed to conduct
geo-epidemiological surveys to identify the most important regions for action and rationalise expenditure on
control. In order to cover more people, the diagnosis of
HAT will have to be improved. For example, better
understanding of what a positive CATT (Card Agglutination Test for Trypanosomiasis) result means, in the
absence of parasitological confirmation, will be needed
to guide the control strategy to adapt on a local basis
[4]. In a context of eradication, in which prevalence may
be very low, efficient surveillance systems will have to
be established based on more sensitive tests for host
exposure to the parasite (e.g. the trypanolysis test) or
the vector (e.g. assaying antibodies against tsetse saliva).
Treatment will be effectively dispensed and made accessible to all the sick, even those in the most remote
areas. It will also be important to consolidate communities’ capabilities in terms of advocacy, consciousnessraising, education and information.
Improving international coordination in HAT control
and prevention will be essential, notably through the
establishment of an integrated, multidisciplinary
approach at the regional level but also by bringing in
new collaborators, from both public and private sectors,
from both hemispheres e.g. WHO, Pan African Tsetse
and Trypanosomiasis Eradication Campaign (PATTEC),
National Sleeping Sickness Control Programme, Institut
de Recherche pour le Développement (IRD), etc. In
West Africa, efforts will have to be geographically
focused on Guinea, the West African country that is
most severely affected by HAT. Moreover, efforts will
have to cover Ivory Coast where the disease is still endemic despite massive control efforts in recent years as
well as other countries i.e. Guinea-Bissau, Liberia, Sierra
Leone and Senegal for which no epidemiological data
are available. In countries where HAT is no longer a
public health problem, epidemiological surveillance will
have to be maintained because the risk of re-emergence
still exists due to the presence of the vector and to
increasing immigration within the region [5].
In the second session, the participants fruitfully discussed the consequences of malaria in pregnant women
and foetal outcomes. An assessment of intermittent preventive treatment (IPT) for malaria in pregnant women
conducted in various settings in Benin showed a sharp
increase in IPT coverage as of the launch of follow-up
in 2006, but coverage was still far below the objective of
Page 2 of 4
80% recommended by WHO and the National Malaria
Control Programme (NMCP) (D’almeida T, et al, Field
evaluation of the intermittent preventive treatment of
malaria during pregnancy (IPTp) in Benin: evolution of
the coverage rate since its implementation, submitted)
[6]. The results showed disparities, with better coverage
in the north and in rural areas than in the south and in
urban settings. Difficulties were also noted with drug
handling and supply, especially in maternity units in
southern towns. Taken together, these results point to
the need for effective assessment at the national level,
ideally through collaborations between research institutions and the NMCP. It has been recommended to
improve the dispensing and supervision of IPT (two
effective doses) by ensuring the drug supply and by consolidating the training of dispensary and hospital staff.
Other findings showed that, for IPT, mefloquine (MQ)
was as effective as SP at preventing low birth weight [7].
Moreover MQ was more effective than SP at preventing
both placental malaria infection and maternal anaemia
at delivery. Mefloquine can be seen as a promising alternative drug for the prevention of malaria in pregnant
women although further data are required on safety and
compliance. Given the development of drug resistance
(e.g. Chloroquine, SP, artemeter and artesunate) in
malaria parasites across the world, it has been emphasized that researchers and NMCPs will have to establish
active surveillance systems to monitor resistance to antimalarials and investigate the underlying mechanisms of
action. Research of alternative preventive methods, especially vaccines is also urgently required in the perspective of malaria elimination.
The results of a regional REFS-FSP project http://
www.ambafrance-bj.org/france_benin confirm that the
new-born babies of mothers infected with Plasmodium
falciparum at delivery are particularly susceptible to
malaria [8]. Important findings were reported on the
role of genetic, immunological and environmental factors in malaria infection that will help in the development of a new candidate vaccine for young children in a
few years. Moreover, an IRD team in Benin showed that
a candidate vaccine during pregnancy, VAR2CSA, was
able to induce a protective immunological response.
More laboratory and field studies are needed to evaluate
the performances and acceptability of this vaccine in
pregnant women.
Session 3, dealing with innovative strategies for malaria
vector control, emphasized the inexorable rise in the
resistance of malaria vectors to insecticides and the consequences for malaria control in Africa based on treated
mosquito nets (ITNs) and indoor residual spraying (IRS).
Given the widespread resistance to pyrethroids in malaria
vectors [9], these molecules seem unsuitable for indoor
spraying operations. Recommendations were made to
Corbel and Henry Parasites & Vectors 2011, 4:37
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keep pyrethroids for mosquito net treatment only in
order to minimize the risk of selection on existing resistance genes. Some scientists suggested including new
vector control (VC) tools in the prevention of malaria,
e.g. long-acting insecticide materials, tarpaulins or wallcoverings such as Durable Wall Lining (DL). The latter
showed particularly promising results in Angola as substitutes to IRS because they required lowest investments in
terms of human and financial resources. However, this
type of material is currently available with pyrethroids
only, so that there is a need to use other classes of insecticide for treatments, e.g. carbamates, pyrroles, neonicotinoids and/or growth regulators. Furthermore, there have
been a number studies exploring the potential for using
entomopathogenic fungi as novel biopesticide interventions against adult malaria mosquito vectors. Recent findings showed that fungal pathogens do not suffer cross
resistance with chemical insecticides and can even exhibit
insecticide resistance-breaking properties, highlight the
potential for use of insect fungal pathogens within novel
strategies of integrated vector management [10]. Beyond
these innovative tools, it was also recommended to conduct more field evaluations on the performances of new
VC strategies on malaria disease. In Benin, a randomised,
controlled trial conducted in Southern Benin showed no
benefit when combining carbamate IRS with LLIN on the
reduction of transmission, prevalence of infection and
malaria attacks in children aged less than six years [11,12].
Increased pyrethroid resistance, inconsistent ITN use and
significant outdoor transmission were suspected to be
responsible for the absence of mass community effects
with combined residual interventions. Researches will thus
have to focus on behavioural changes in malaria vectors
after VC operations and to identify complementary methods to better target exophagous and exophilic mosquito
populations (e.g. new attractant traps, push-pull strategies,
treating of resting areas, larvicidal operations, etc.).
An important point raised by the scientists was to
include also social sciences into all entomo-epidemiological evaluations of new VC tools. In the same way,
bringing local people in when compiling “Study Protocols” and preparing VC operations is essential to guarantee local support and commitment for the project. It
is obvious that consciousness-raising campaigns (radio,
television, posters, etc.) are key points when it comes to
improving the acceptance of VC tools such as LLIN
which remains the main way of community-based prevention in Africa. Improvements may be useful as well
on the criteria and indicators used to evaluate VC, especially to better reflect human-vector contact after implementation of an intervention. A newly developed
immunological biomarker that measures specific exposure of subjects to the vector proved to be highly sensitive in the evaluation of a massive ITN distribution
Page 3 of 4
campaign in Angola at both the community and individual levels [13]. This new “salivary” biomarker could be
ideal for evaluating control programmes and would cut
down the need for human capture methods which pose
both ethical and logistic problems.
Considering the amounts invested in malaria and
HAT prevention and control in the last decade (by the
World Bank, the Global Fund, the President’s Malaria
Initiative, the Bill & Melinda Gates Foundation, etc.), a
rigorous, multidisciplinary evaluation of the public
health programmes is indispensable. The evaluation will
have to include both VC interventions and antimalarial
drugs (CTA, SP, etc.), the monitoring of vector resistance to insecticides and parasite resistance to drugs,
the estimates of compliance, safety and the acceptance
of treatments by populations. Building the capacities in
medical entomology, parasitology, epidemiology, immunology, at research institutions, universities and national
control programmes will also be a priority. This could
be achieved through collaborative research programmes,
the founding of federative research laboratories (e.g. the
Centre de Lutte Intégrée contre le Paludisme in Benin),
effective training programmes and the establishment of
International Master’s Degrees (e.g. the International
Master’s Degree in Entomology http://www.miemv.org.
IRD is, for example, supporting the creation of International Mixed Laboratories (LMI) and young associate
teams (JEAI) to help scientists from the South to
develop their research programmes http://www.ird.fr.
Before the world is rid of malaria and neglected diseases,
research institutes and national control programmes will
have a key role to play in the prevention and control of
these diseases. It is therefore important to strengthen
research and training capacities in the South, and foster
synergistic interactions between the different actors to
promote strategic decision-making in public health.
Additional material
Additional file 1: Proceedings of the international symposium.
Additional file 2: Scientific Committee.
Acknowledgements
The authors are very grateful to André Garcia, Nadine Fievet, Franck
Remoué, Thierry Baldet, Vincent Jamonneau, Bruno Bucheton and Philippe
Solano for their contribution to this work. This symposium received
institutional sponsorships from IRD, the French Ministry of Foreign Affairs
(MAEE), CREC, FSS, ISBA, IRSP, NMCP, USAID in Benin, CIRDES and NSSCP
from Burkina Faso and NSSCP from Guinea. Thanks to IRD (UMR 224, UMR
216 and UMR 177), the French Embassy in Benin (SCAC) and private partners
(Bayer Environmental Science, Vestergaard frandsen, Sumitomo Chemical &
Sanofi-Aventis) for their financial support.
Author details
Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604,
Cotonou, Bénin. 2Institut de recherche pour le développement (IRD),
1
Corbel and Henry Parasites & Vectors 2011, 4:37
http://www.parasitesandvectors.com/content/4/1/37
Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle
(MIVEGEC), UM1-CNRS 5290-IRD 224, 01 BP 4414 RP Cotonou, Bénin. 3Service
de Coopération et d’Action Culturelle, Ambassade de France, Cotonou,
Bénin.
Page 4 of 4
doi:10.1186/1756-3305-4-37
Cite this article as: Corbel and Henry: Prevention and control of malaria
and sleeping sickness in Africa: Where are we and where are we going?
Parasites & Vectors 2011 4:37.
Authors’ contributions
VC and MCH led the organization and scientific committees of the
International Symposium on Malaria and Human African Trypanosomiasis: New
Strategies for their Prevention & Control and wrote the meeting report. All
authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 7 March 2011 Accepted: 16 March 2011
Published: 16 March 2011
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